Question

PCBs are a possible environmental contaminant from industry and legislation to restrict PCBs was put into place in the 1970s. In order to check the effectiveness of the legislation Great Lakes herring eggs were collected were collected randomly and the level of PCBs in the shell was measured. These samples were taken over several years and the following table summarizes two of those years. Does this data show a significant decrease in the PCB levels between 1982 and 1996? Use a 0.05 significance level.

	N	Sample Mean	Std Dev
PCB content in 1982	13	54.33	15.65
PCB content in 1996	13	15.52	5.96

Answer 1